A determination of the primary sequence of T2 induced deoxycytidylate deaminase will be undertaken. Various methods will be used to cleave the protein at specific amino acid residues to provide peptides of different sizes and of overlapping sequences. From the information obtained on the sequence of individual peptides it should be possible to establish the complete primary sequence of the enzyme. Purification of deoxycytidylate deaminase from a human source, He La cells, is being pursued. When adequate quantities of the homogeneous enzyme are available a comparison of amino acid compositions and peptide maps from it and the T2 induced enzyme will be made.